Update requirements.txt (salesforce#40)

* Update requirements.txt

* update doc.yml workflow

* Revert "update doc.yml workflow"

This reverts commit 794ef3a.

* Update build_docs.sh

adding documentations for methods, dataclasses etc (salesforce#24)

* adding documentations for methods, dataclasses etc

* fixed typo in drain (renaming of add_log_message to _add_log_message)

* fixed sphinx doc errors/warnings

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Co-authored-by: Qian Cheng <[email protected]>